Bombing effects on invading troops

[swagman]

Consider a base being invaded. The base is bombed and suffers base damage and troop loss. If engineers are present, they will automatically repair the damage and use up supplies.

The invading force has landed supplies, so presumbably they have huge amounts of supplies exposed and vulnerable to air attack. They get bombed and it seems only the ground units are hit. They suffer no loss of supply, it seems. Nor do they have to expend supplies on maintaining the beach (ie fixing roads, dispersing supplies, etc).

In addition, both forces seem to suffer similar rates of casualties, although the forces in the base would presumably have much better bomb shelters and bunkers and supply storage.

This seems to me to give a significant advantage to an invading force, when compared to the base defenders.